3d printed semiconductor package

ABSTRACT

In described examples, a method for encapsulating a semiconductor device includes the steps of immersing a layer of the semiconductor device in a liquid encapsulation material, irradiating portions of the liquid encapsulation material to polymerize the liquid encapsulation material, and moving the semiconductor device further from a surface of the liquid encapsulation material proximate to the layer. Immersing the semiconductor device is performed to cover a layer of the device in the liquid encapsulation material. Targeted locations of the liquid encapsulation material covering the layer are irradiated to form solid encapsulation material. The semiconductor device is moved from a surface of the liquid encapsulation material so that a new layer of the semiconductor device and/or of the solid encapsulation material can be covered by the liquid encapsulation material. The irradiating and moving steps are then repeated until a three dimensional structure on the semiconductor device is formed using the solid encapsulation material.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.16/236,099 filed Dec. 28, 2018, which is incorporated herein byreference.

BACKGROUND

This relates to packaging of semiconductor devices, and moreparticularly to encapsulating semiconductor device packages.

FIG. 1 shows an example view 100 of an object 102 being formed with vatphotopolymerization (VP). VP is also called, for example,stereolithography apparatus (SLA), digital light processing (DLP), scan,spin and selectively photocure (3SP), and continuous liquid interfaceproduction (CLIP). VP can be used to make 3D objects in desired shapes.In VP, an object 102 is fabricated using a basin 104 containing a fluidbath of liquid photopolymer resin 106 (the object 102 shown correspondsto a design for an object in the process of being fabricated). The resin106 is cured at selective locations for a given surface layer of theresin 106 and using targeted light exposure from a light source 108. Forexample, using DLP (digital light processing, which uses digitallycontrolled micromirrors) to control illumination and curing of the resin106, photon sources 110 can be targeted to locations at the surface ofthe resin 106 bath. Targeting is accomplished using precisely controlledmicromirrors 112 (such as using DLP or mirror galvanometers). After alayer of resin 106 is cured corresponding to a cross-section of thedesigned object, the object-in-process (the layers already fabricated)can be moved away (i.e., downward or upward) from the surface of theresin 106, and the resin 106 can be selectively illuminated and cured tofabricate the next layer (cross-section) of the designed object.

SUMMARY

In described examples, a method for encapsulating a semiconductor deviceincludes the steps of immersing a layer of the semiconductor device in aliquid encapsulation material, irradiating portions of the liquidencapsulation material to polymerize the liquid encapsulation material,and moving the semiconductor device further from a surface of the liquidencapsulation material proximate to the layer. Immersing thesemiconductor device is performed to cover a layer of the device in theliquid encapsulation material. Targeted locations of the liquidencapsulation material covering the layer are irradiated to form solidencapsulation material. The semiconductor device is moved from a surfaceof the liquid encapsulation material so that a new layer of thesemiconductor device and/or of the solid encapsulation material can becovered by the liquid encapsulation material. The irradiating and movingsteps are then repeated until a three dimensional structure on thesemiconductor device is formed using the solid encapsulation material.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example view of an object being formed with vatphotopolymerization (VP).

FIG. 2A schematically shows an example of a cross-sectional view ofsemiconductor device encapsulation using top-down VP.

FIG. 2B schematically shows an example of a cross-sectional view of asemiconductor device 202.

FIG. 2C schematically shows an example of a cross-sectional view ofsemiconductor device encapsulation using top-down VP.

FIG. 2D schematically shows an example of a cross-sectional view of anencapsulated semiconductor device after the device is removed from thepolymer resin basin.

FIG. 3A shows an example of a side elevational view of multipleencapsulated dies on a single substrate.

FIG. 3B shows an example of a top-down view of the multiple encapsulateddies on a single substrate of FIG. 3A.

FIG. 3C shows an example of a perspective view of the multipleencapsulated dies on a single substrate of FIG. 3A.

FIG. 4 schematically shows an example of a cross-sectional view ofstacked semiconductor dies with a selective cavity around the top die.

FIG. 5A schematically shows an example of a cross-sectional view ofsemiconductor device encapsulation using bottom-up VP.

FIG. 5B schematically shows an example of a cross-sectional view ofsemiconductor device encapsulation using bottom-up VP.

FIG. 6A schematically shows an example of a cross-sectional view of anencapsulated semiconductor device.

FIG. 6B schematically shows an example of a cross-sectional view of asemiconductor device encapsulated using VP.

FIG. 7A schematically shows an example of a cross-sectional view of asemiconductor device encapsulated using VP.

FIG. 7B schematically shows an example of a top-down cross-sectionalview of a semiconductor device encapsulated using VP.

FIG. 8 schematically shows an example of a cross-sectional view of asemiconductor device encapsulated using VP.

FIG. 9A schematically shows an example of a cross-sectional view offabrication, using VP, of positive molds used to fabricate inductors onthe same substrate as used for fabrication of integrated circuits.

FIG. 9B schematically shows an example of a cross-sectional view ofinductors fabricated on a substrate on which integrated circuits arealso fabricated.

FIG. 9C schematically shows an example of a cross-sectional view of adevice with an inductor integrated on the same substrate surface, andincorporated into the same encapsulated package, as an IC.

FIG. 10A schematically shows a cross-section of an example of asemiconductor device with an antenna integrated into the sameencapsulated package, and on the same substrate, as an IC.

FIG. 10B schematically shows a cross-section of an example of asemiconductor device with specified three-dimensional shapes integratedinto the same encapsulated package, and on the same substrate, as an IC.

FIG. 11A shows an example of a process for encapsulation of asemiconductor device using vat polymerization.

FIG. 11B shows an example of a process for incorporation into asemiconductor device package of three-dimensional structures plated ontoVP-formed positive molds.

FIG. 12 shows an example of a process for encapsulating a semiconductordevice using VP.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

FIG. 2A schematically shows an example of a cross-sectional view 200 ofsemiconductor device 202 encapsulation using top-down VP (vatphotopolymerization). As shown in FIG. 2A, in top-down VP, the fluidbath of resin 106 in the basin 104 is preferably (at least) as deep asthe intended structure to be fabricated on the target object—thesemiconductor device 202—is tall.

FIG. 2B schematically shows an example of a cross-sectional view of asemiconductor device 202. A semiconductor device 202 can comprise, forexample, an IC 210 (an integrated circuit, also referred to as a die)mounted on a die pad 212 and fixedly attached to the die pad 212 usingan attaching material 214, such as epoxy die attach. The IC 210 iselectrically connected to lead fingers 216 by wires 218. In someembodiments, wires 218 can also electrically connect the die pad 212 tothe IC 210, and/or electrically connect the die pad 212 to the leadfingers 216. The die pad 212 and lead fingers 216 can be used to connectthe IC 210 to a packaging substrate or to a lead frame (such as aquad-flat no-lead frame, or QFN). The lead frame connects the IC 210 toan external system such as the surface of a printed circuit board.

Referring to FIG. 2A, the semiconductor device 202 is attached to amechanical stage capable of vertical movement and lowered into the resin106. The IC 210 can be lowered into the basin 104 by lowering in apackaging substrate or lead frame on which the IC 210 is mounted, or theIC 210 itself.) The device 202 starts at a level in the resin 106 bathcorresponding to a first layer 204 of resin 106 to be washed onto andthen cured onto the device 106. After a layer 204 (as shown, the areawithin the dotted-line box) of un-cured resin 106 is washed onto thecurrent surface of the device 202 (the surface including polymerizedresin 206), selected locations of the layer 204 are exposed to(illuminated/irradiated with) light 208 or some other energy source. Thelight 208 causes the resin 106 to cure, forming polymerized resin 206,so that the first instance of such a cure commences the encapsulation ofcured resin onto device 202. After the layer 204 of resin 106 is cured(polymerized) onto the device 202, the device 202 is lowered, beneath aninterface between the liquid photopolymer resin and an atmosphereexterior to the basin 104, by a height interval corresponding to a nextlayer 204 of resin 106 to be washed and cured onto the device 202. Theheight interval can correspond to, for example, sizes of features to becreated using VP, or VP feature size limits, or feature sizes ofstructures on the device 202. Resin 106 can be cured with features sizesof, for example, 20 μm to 200 μm.

As layers of resin 106 are cured to form additional encapsulation andthe device 202 is further submerged incrementally, layer 204 by layer204, in the resin 106 bath, the photopolymer resin 106 may not fullywash over—or may wash over in excess—a portion of the device 202currently being targeted for material deposition. Prior to curing, adoctor blade (similar to doctor blades used in rotogravure printing) canbe used to sweep photopolymer resin 106 onto the device 202 if the layer204 currently being processed is not fully covered, and/or to sweepexcess resin 106 back into the basin 104. Alternatively, ultrasonicenergy can be used to break up surface tension of the resin 106,enabling the resin 106 to find its lowest energy position on thesemiconductor device 202 (preferably, evenly coating the layer 204currently being processed). Repeated cures of successive layers 204 ofresin 106 washed onto the device 202 can be used to encapsulate thedevice 202 and thereby create an overmold 220 (shown in FIG. 2C)comprising polymerized resin 206.

A resin 106 can include, for example, monomers, dimers, trimers, orlarger arrangements of polymers, which can be cross-linked using appliedenergy. Energy can be applied using, for example, light, heat, ion beamsor electron beams. The polymerizing portion of the resin 106 can includevarious materials, such as acrylate, epoxy or polyimides. The resin 106can also include filler particles which are, for example, 1 nm to 100 μmin size, composed of, for example, oxides, carbon/carbon allotropes,ceramics or metals. Multiple baths with different photopolymers can beused to create a final product comprising multiple different curedmaterials having different properties (e.g., different hardnesses,textures or heat conduction properties).

FIG. 2C schematically shows an example of a cross-sectional view 222 ofsemiconductor device 202 encapsulation using top-down VP. As shown bythe sequence of FIGS. 2A and 2C, exposure of a layer 204 of resin 106 tolight 208 results in that layer 204 of resin 106 being cured, formingpolymerized resin 206. VP enables fabrication of physically and/orelectrically functional structures in die 210 packaging, and, moregenerally, in semiconductor device 202 packaging.

FIG. 2D schematically shows an example of a cross-sectional view 224 ofan encapsulated semiconductor device 202 after the device 202 is removedfrom the polymer resin basin 104. The polymerized resin overmold 220 canbe fabricated, using selective curing in the top-down VP steps, tocreate different surface shapes and/or internal cavities. For example,as shown in FIG. 2D, tubular hollow regions 226 can be left around thewires 218 so that the overmold 220 does not contact the wires 218. Thishelps to prevent wire bend delamination. Also, holes or other cut-outshapes can be formed by leaving uncured selective locations in thepolymerized resin 206. Holes can be used to mitigate stress on a die 210surface caused by, for example, externally applied stressors or as aresult of internal deformation caused by thermal variance.

Vat polymerization enables high resolution printing of encapsulationmaterial with three-dimensional features with high throughput. Printablefeatures include cavities and other three-dimensional structures, asfurther described with respect to, for example, FIGS. 3A through 8 andFIG. 11A. Vat polymerization also enables printing of a variety ofthree-dimensional shapes, including for use as positive molds forfunctional features, as further described with respect to, for example,FIGS. 9A, 9B, 10A, 10B, and 11B.

FIG. 3A shows an example of a side elevational view 300 of multipleencapsulated dies 210 on a single substrate 302. FIG. 3B shows anexample of a top-down view 304 of the multiple encapsulated dies 210 ona single substrate 302 of FIG. 3A. FIG. 3C shows an example of aperspective view 306 of the multiple encapsulated dies 210 on a singlesubstrate 302 of FIG. 3A. As shown in FIGS. 3A, 3B and 3C, because resin106 can be polymerized at specified locations, different devices 202 canbe encapsulated differently. Accordingly, the polymerized resin 206encapsulating a device 202 can comprise features that are unique to thatdevice 202, with respect to a run of devices 202 using a same designlayout database (specifying device 202 features such as interconnectsand doped regions). For example, each device 202 in a fabrication runcan comprise an overmold 220, made using polymerized resin 206, with oneor more features unique to that device 202 with respect to the otherdevices 202 in the run. Features which are unique per-device in aproduction run, and/or which are different for different groups ofdevices in a production run, can include, for example: a numberidentifying the part, or its corresponding batch or lot; structuretuning the device's 202 thermal or other performance characteristicspursuant to a customer order; a die-specific identifier; oranti-counterfeit patterns, such as patterns which are internal to(buried under the surface of) respective overmolds 220 and which areunique to each device 202. While in some embodiments an Eiffel Tower maynot be a preferred packaging shape, use of Eiffel Towers in FIGS. 3A, 3Band 3C makes a point regarding the versatility of VP as a tool forencapsulation of semiconductor devices 202.

FIG. 4 schematically shows an example of a cross-sectional view 400 ofstacked semiconductor dies 210 with a selective cavity 402 around thetop die 210. As shown in FIG. 4, Dies 210 can be stacked on top of eachother within a packaged device 202, with an adhesive 404 (which can be,but is not necessarily, conductive) connecting them, and with aselectively produced cavity 402 (as discussed below with respect to, forexample, FIGS. 6A and 6B) surrounding the top die 210. Preferably, dies210 which are vertically superior (above) to other dies 210 in a stackwith respect to a substrate surface (not shown) are successively smallerthan dies 210 which are vertically inferior (below) with respect to thesubstrate surface. Stacked dies 210 can be electrically connected bywires 218. The cavity 402 around the top die 210 prevents stressesapplied to the packaged device 202 from affecting performance of thestacked dies 210 (in some embodiments, performance is sensitive tostress), and generally enables higher precision in fabrication andperformance.

FIG. 5A schematically shows an example of a cross-sectional view 500 ofsemiconductor device 202 encapsulation using bottom-up VP. In bottom-upVP, the basin 104 is transparent, for example, made of glass. The device202 is attached to a mechanical stage capable of vertical movement andsubmerged in the resin 106, with the portion of the device 202 to beilluminated (to thereby cure contiguous resin 106) facing a wall of thebasin 104 (preferably, the bottom of the basin 104) and held at adistance from that wall such that a layer 204 of resin 106 is availableto be cured in specified locations.

As shown in FIG. 5A, the resin 106 in a current layer 204 is irradiated,and then pried off the glass/polymer connection between newlypolymerized resin 206 and the basin 104 wall (for example, using ashimmying motion). The device 202 is then raised (moved away from aninterface between the liquid photopolymer resin and the basin 104 wall)so that resin 106 is available to (preferably, only to) the next layer204 to be treated, and the process is repeated.

FIG. 5B schematically shows an example of a cross-sectional view 502 ofsemiconductor device 202 encapsulation using bottom-up VP. As shown inFIG. 5B, a transparent wall of the basin 104 can comprise an O₂permeable glass (O₂ will typically inhibit the polymerization reactionof the resin 106) or other reaction inhibitor. Using a basin 104 withwalls comprising, treated with, or transmitting a polymerizationinhibitor creates a region 504 near the basin 104 walls wherepolymerization will not occur (or occurs much more slowly), despiteillumination by the light source 208. This enables encapsulatingpolymerization to occur away from the basin 104 walls, avoidingshimmying (or otherwise stressing) the device 202 to separatenewly-formed polymerized resin 206 from the basin 104 walls. Relevantsubject matter describing bottom-up fabrication techniques using apolymerizable liquid can be found in U.S. Pat. Pub. No. 2014/0361463,which is incorporated herein by reference.

FIG. 6A schematically shows an example of a cross-sectional view 600 ofan encapsulated semiconductor device 202. As shown in FIG. 6A, a cavity602, filled with air or another gas or liquid (or mixture), can befabricated around the die 210 using VP. The cavity 602 can be configuredto prevent stress from package flexion due to, for example, thermalexpansion.

FIG. 6B schematically shows an example of a cross-sectional view 604 ofa semiconductor device 202 encapsulated using VP. As shown in FIG. 6B,using VP, a cavity 602 can be fabricated around the die 210 (duringencapsulation) to contain an object 606—accordingly, a selected threedimensional structure which is connected or unconnected to the body ofthe encapsulating material (the overmold 220). The contained object canbe, for example, a sensor component, such as a ball for anaccelerometer. The object 606 can be made of any solidmaterial—preferably, a material which will not react with thepolymerized resin 206—such as polymerized resin 206, a metal, a ceramic,a plastic or a semiconductor.

During VP, the device 202 can be removed from and re-immersed into theresin 106 bath between deposition of layers 204. This provides anopportunity to drain cavities 602, (optionally) fill them with a gas,liquid, solid material, object, or a combination thereof, and cap(enclose) the cavities.

FIG. 7A schematically shows an example of a cross-sectional view 700 ofa semiconductor device 202 encapsulated using VP. As shown in FIG. 7A,material can be polymerized using VP in patterned layers that leaveinternal channels 702 in the encapsulating polymerized resin 206. Thesechannels can be configured to enable, for example, microfluidics, whichcan be used to cool the device 202. Similarly, vertical channels can beused as light pipes, to enable direct emissions and/or sensing by thedevice 202. This can be used for (for example) light emitting junctions,sensors, and communications.

FIG. 7B schematically shows an example of a top-down cross-sectionalview 704 of a semiconductor device 202 encapsulated using VP. As shownin FIG. 7B, microfluidic channels 702 can lead into and out of anovermold 220 encapsulating a device 202. Microfluidic channels 702 canbe used to distribute a cooling medium into and out of the device 202.

FIG. 8 schematically shows an example of a cross-sectional view 800 of asemiconductor device 202 encapsulated using VP. As shown in FIG. 8, VPcan be used to create a button 802 and an empty space 804 underneath thebutton 802. The button 802 can be configured to toggle a state of thedevice 202, enabling the packaged device 202 itself to be used as, forexample, an input/output (I/O) device.

FIG. 9A schematically shows an example of a cross-sectional view 900 offabrication, using VP, of positive molds 902 used to fabricate inductors904 (shown in FIG. 9B, not in FIG. 9A) on the same substrate 906 as usedfor fabrication of integrated circuits 210 (not shown). A positive moldtypically includes a cutout shape which is filled with a liquidsubstance that is poured into the cutout and hardens in the shape of thecutout. A positive mold is essentially a scaffold constructed in thedesired shape, so that a substance coated onto the positive mold willassume the desired shape. FIG. 9B schematically shows an example of across-sectional view 908 of inductors 904 fabricated on a substrate 906on which integrated circuits 210 (not shown) are also fabricated.

As shown in FIGS. 9A and 9B, VP can be used to create positive molds 902of inductors 904 on the surface of a wafer or other substrate 906 onwhich integrated circuits 210, comprising functional electroniccomponents (for example, a processing device, such as switching andother components comprising a DC-DC power converter), are alsofabricated. The positive molds 902 comprise polymerized resin 206,shaped such that metallizing techniques (such as electroplating) can beused to coat the polymerized resin 206 with a selected metal (or otherappropriate material) to create inductors 904, as shown in FIG. 9B. Toform inductors 904, positive molds can be coated with, for example, thesame metal(s) as used to make one or more metal stack layers, and anexterior layer can comprise passivation.

The resin 106 used to form the positive molds 902 preferably includes acatalyst such that the polymerized resin 206 in the positive molds 902enables and/or improves coating of the positive molds 902 with thecoating material. Coating of the positive molds 902 can be performedusing, for example, electroplating, with design rules selected such thatthe resulting inductor 904 is functional (for example, avoiding shortcircuits). Mass transport theory can be used to facilitate such design.Cladding is preferably followed by laying down an insulating layer overthe coating material using, for example, chemical vapor deposition.

The inductors 904 can then be heated (annealed) to form conductive bondswith metal pads on their carrying substrate 906. The substrate 906 cansubsequently be cut so that an inductor remains electrically connectedto a respective IC 210, facilitating packaging of inductors 906 as partof an integrated semiconductor device 202. Inductors 906 fabricated asshown in FIGS. 9A and 9B can be encapsulated with an IC 210 using VPprocesses as described with respect to FIGS. 2A, 2B, 4, 5A, and 5B.

Inductors 906 and other functional structures fabricated as shown inFIG. 9A and 9B (such as antennas 1002, as described with respect to FIG.10A, or other functional 3D structures, as described with respect toFIG. 10B) can be fabricated on the same die 210, a different die 210, oron the same lead frame or packaging substrate as the die 210 included ina co-encapsulated semiconductor device 202 (as shown in FIG. 2A).

FIG. 9C schematically shows an example of a cross-sectional view 910 ofa device 202 with an inductor 904 integrated on the same substrate 906(not shown) surface, and incorporated into the same encapsulatedpackage, as an IC 210.

FIG. 10A schematically shows a cross-section of an example 1000 of asemiconductor device 202 with an antenna 1002 integrated into the sameencapsulated package, and on the same substrate 906 (not shown), as anIC 210. Use of VP to create a positive mold 902 for then forming anantenna 1002 enables fabrication of the antenna 1002 on-die of aspecified length, and with a sufficient separation between the receivingand/or transmitting arm of the antenna 1002 and the IC 210 to enableefficient antenna 1002 function. After the antenna 1002 is fabricated,it can be annealed (heated) to create an electrical connection to ametal pad on the IC 210 on which the antenna 1002 is fabricated.

FIG. 10B schematically shows a cross-section of an example 1004 of asemiconductor device 202 with specified three-dimensional shapes 1006integrated into the same encapsulated package, and on the same substrate906, as an IC 210 (not shown). As shown, VP can be used to fabricate avariety of three dimensional shapes 1006 on-die, which can then beincluded for encapsulation in a single package with an IC 210 containingelectrically functional circuits. VP can be used to create positivemolds 902 using polymerized resin 206. The positive molds 902 are thencoated with a desired surface material 1008. A surface material 1008coating can include a metal coating fabricated using electroplating,thereby completing the three-dimensional shape 1006.

FIG. 11A shows an example of a process 1100 for encapsulation of asemiconductor device 202 using vat polymerization. As shown in FIG. 11A,photopolymer resin 106 is caused to wash over a layer of the device 202onto which resin 106 will be polymerized in step 1102. Specifiedportions of the resin 106 are then irradiated with light 208 topolymerize the resin 106 in step 1104. After polymerization, the device202 is moved deeper into the basin 104 containing the resin 106 (movethe device 202 down into the basin 104 in top-down VP, and upwards fromthe bottom of the basin 104 in bottom-up VP) in step 1106. If there areadditional layers 204 to polymerize, the process is then repeated fromstep 1102.

FIG. 11B shows an example of a process 1110 for incorporation into asemiconductor device package 202 of three-dimensional structures platedonto VP-formed positive molds. As shown in FIG. 11B, vat polymerizationis used to fabricate, on the substrate 906 on which, or in connectionwith, a semiconductor device 202 will be fabricated, a positive mold 902of a desired electrically functional structure for incorporation into asemiconductor device package, in step 1112. The positive mold 902 iscoated with metal using electroplating in step 1114. The coatedstructure is then annealed onto metal pads on the substrate 1108 toelectrically connect the structure in step 1116. The semiconductordevice 202 is subsequently fabricated on the substrate 906 in step 1118.The substrate 906 is cut into sections for packaging in step 1120, andthe functional structure is encapsulated (packaged) with thesemiconductor device, preferably using VP, in step 1122.

FIG. 12 shows an example of a process 1200 for encapsulating asemiconductor device 202 using VP. In step 1202, a surface of thesemiconductor device 202 is imaged; for example, optically,acoustically, or using a charged particle beam. In step 1204, theresults of the imaging are compared to a design layout database of thesemiconductor device 202 to determine as-written locations ofsemiconductor device 202 features. By determining where semiconductorfeatures have actually been written, encapsulation can be restricted toactual feature locations, rather than enclosing feature locationtolerances. Accordingly, for example, if a device 202 has a 1 mm×1 mmpillar which is written with a 1 mm×1 mm tolerance, by imaging thedevice 202 prior to polymerizing a layer 204 of resin 106 around thepillar, the resin 106 can be polymerized around the more precise arearesulting from the imaging (conforming to the 1 mm×1 mm pillar), ratherthan the 2 mm×2 mm potential write location of the pillar.

In step 1206, a layer 204 of liquid photopolymer 106 is applied to thesurface of the semiconductor device 202. In step 1208, parameters to beused and/or locations to be targeted in polymerizing the layer 204 aremodified, in dependence on the step 1202 imaging and the step 1204comparing. Modified parameters can include, for example, lightintensity, duration of light exposure, and location(s) of lightillumination on the substrate. In step 1210, targeted portions of thelayer 204 of liquid photopolymer resin 106 are polymerized usingtargeted applied energy, using the modified parameters and/or locationsfrom step 1208, to form a specified layer 204 of solid polymerized resin206 mechanically coupled to the semiconductor device 202. The process isrepeated from step 1202 to form a specified three-dimensional shapeencapsulating the semiconductor device.

The process 1200 can also include error correction to improve processfidelity from one layer 204 to a next layer 204. To accomplish this, thestep 1202 imaging includes imaging the solid polymerized resin 206produced in step 1210, and the step 1204 comparing includes comparingresults of the imaging to a design layout database of the semiconductordevice 202 and of the three-dimensional shape to locate placement errorsof the solid polymerized resin 206. The modifying step then takes theresults of this additional comparing into account to correct forpolymerization process errors in future layers 204.

The described innovations, in various embodiments, provide one or moreof at least the following advantages. However, not all of theseadvantages result from every one of the innovations described, and thislist of advantages does not limit the scope of this description.

-   -   Enables semiconductor device packaging with internal structure;    -   enables physically functional structures in semiconductor device        packaging;    -   enables packaging that mitigates physical and thermal stress on        packaged semiconductor devices;    -   enables packaging of integrated circuits incorporating        microfluidic channels;    -   enables packaging of inductors with integrated circuits;    -   enables packaging of antennae with integrated circuits;    -   enables packaging of integrated circuits such that the packaging        incorporates specified three dimensional structures; and    -   enables packaging of integrated circuits such that the packaging        incorporates specified metal-coated three dimensional        structures.

Methods, devices and systems are described for packaging semiconductordevices using vat polymerization. Polymerization can be restricted tolocations designated for illumination. Different polymers with differentproperties can be incorporated by encapsulating a semiconductor deviceusing multiple different resins, different resins being located indifferent resin baths. Different polymers can be used to fabricatedifferent 3D locations of the polymer encapsulation, enabling targetedpositioning of material properties within layers of device-encapsulatingmaterial. Consequently, various functional structures can be fabricatedwithin, on the surface of and through encapsulating polymerized resin.

Methods, devices and systems are described for using vat polymerizationto fabricate functional structures for incorporation into semiconductordevice packaging. A positive mold can be fabricated on a substrate. Thepositive mold can then be coated in a desired material, e.g., coatedwith metal using electroplating. The metallized structure is thenthermally annealed onto metal pads on the substrate. After the substrateis cut, the metallized structure can be electrically connected to, andincorporated into the same encapsulating packaging as (e.g., using VP),a semiconductor device.

In some embodiments, a cavity created during encapsulation using VP cancontain an object which is electrically or photonically functional (suchas a reflective object).

In some embodiments, a ceramic can be used instead of a resin asencapsulation material.

In some embodiments, a full oxide shell can be used instead of a resinas encapsulation material.

In some embodiments, a method other than vat polymerization is used toencapsulate an IC.

In some embodiments, a surface of a lead frame or of a die can betreated, prior to VP encapsulation, with an adhesion promoter, toimprove adhesion of polymerized resin to the treated lead frame or die.

In some embodiments, multiple dies can be encapsulated within the sameovermold.

In some embodiments, vat polymerization can be used to create positivemolds of interconnects, so that plating of such positive molds createsinterconnects. Such interconnects can include, for example, connectionsbetween dies, connections between a die and a lead frame, andnon-standard interconnects. Printable non-standard interconnect moldscan be used to form, for example, twisted pair lines, or wires withimpedance (inductance, capacitance, and/or resistance) selected byselecting a wire shape and/or size and/or material.

In some embodiments, a liquid encapsulation material (such as apolymerizable liquid) other than a photopolymer resin is used to performvat polymerization, the liquid encapsulation material chosen to besubject to location-selectable curing by selective irradiation of theliquid encapsulation material.

In some embodiments, an irradiation energy source other than light, suchas charged particles, is used to cure (solidify) a liquid encapsulationmaterial. In some embodiments, parameters which can be modified inperforming VP include intensity (amplitude) of applied energy, durationof irradiation, and location of irradiation.

In some embodiments, VP is used to form a button, for direct humaninterface, which is capable of toggling a state of an IC (by contactwith the IC) when depressed (as further described with respect to FIG.8). In some embodiments, VP is used to form another type of direct humaninterface, such as a toggle, switch, or slider, which is capable ofchanging a state of an IC (by contact with the IC) when interacted withby a user.

Modifications are possible in the described embodiments, and otherembodiments are possible, within the scope of the claims.

What is claimed is:
 1. A method for encapsulating a semiconductordevice, the method comprising: a) immersing the semiconductor device ina liquid encapsulation material such that a specified layer of thesemiconductor device is covered in the liquid encapsulation material; b)irradiating portions of the liquid encapsulation material coveringtargeted locations of the specified layer such that the irradiatedportions polymerize to form solid encapsulation material fixedly coupledrelative to the semiconductor device; c) moving the semiconductor devicefurther from a surface of the liquid encapsulation material proximate tothe specified layer, such that a new specified layer of thesemiconductor device and/or of the solid encapsulation material iscovered by the liquid encapsulation material; and d) repeating the stepsb) and c) until a specified three dimensional structure is formed by thesolid encapsulation material fixedly coupled relative to thesemiconductor device.
 2. The method of claim 1, wherein the liquidencapsulation material is a liquid photopolymer resin and the solidencapsulation material is a solid polymerized resin.
 3. The method ofclaim 1, wherein one or more of the following is formed within the solidencapsulation material: a specified cavity, a specified cavitysurrounding a specified object embedded within the specified cavity, aspecified microfluidic channel, a hollow tube surrounding a wire bondedto a lead frame and to the semiconductor device, a hole connecting andenabling light to be transmitted between a surface of the semiconductordevice and an exterior surface of the solid encapsulation material, anidentifier unique to the semiconductor device, or an anti-counterfeitpattern.
 4. The method of claim 1, wherein a button is formed using thesolid encapsulation material, with a cavity being formed between thebutton and a surface of the semiconductor device, the cavity enablingdepression of the button to toggle a state of the semiconductor device.5. The method of claim 1, wherein the immersing and the moving includeeither lowering the semiconductor device beneath a liquid encapsulationmaterial-atmosphere interface, or moving the semiconductor device awayfrom an interface between the liquid encapsulation material and a wallof a basin containing the liquid encapsulation material.
 6. The methodof claim 1, wherein a wall of a basin containing the liquidencapsulation material includes an O₂-permeable material, and/or amaterial selected to inhibit polymerization of the liquid encapsulationmaterial.
 7. The method of claim 1, wherein steps a), b), c), and d) areperformed with respect to a first basin containing a first liquidencapsulation material, and further comprising repeating steps a), b),c), and d) for each of a plurality of basins, the plurality of basinsincluding the first basin, and wherein each basin in the plurality ofbasins comprises a liquid encapsulation material differing from theliquid encapsulation material in each other basin of the plurality ofbasins.
 8. The method of claim 1, wherein the steps a), b), c), and d)are performed to encapsulate multiple semiconductor devices with thesolid encapsulation material comprising different functional structureson different ones of the multiple semiconductor devices, the multiplesemiconductor devices patterned on a same semiconductor substrate and/orusing a same design layout database.
 9. The method of claim 1, furthercomprising, prior to the step a), pre-treating a surface of thesemiconductor device, and/or of a lead frame to which the semiconductordevice is attached, with an adhesion promotor selected to improveadhesion of the solid encapsulation material to the surface of thesemiconductor device and/or the lead frame.
 10. The method of claim 1,further comprising removing the semiconductor device from the liquidencapsulation material between repetitions of the step a).
 11. Themethod of claim 10, further comprising, while the semiconductor deviceis removed from the liquid encapsulation material, draining and cappinga cavity formed by the steps a), b), c), and d).
 12. A method forencapsulating a semiconductor device, the method comprising: a) coveringa specified layer above a surface of the semiconductor device in liquidencapsulation material; b) irradiating the liquid encapsulation materialin targeted locations such that the liquid encapsulation materialpolymerizes, only at the targeted locations, into a solid encapsulationmaterial fixedly mechanically coupled to contiguous portions of thesemiconductor device and of the solid encapsulation material; and c)repeating the steps a) and b) to form a specified three-dimensionalshape encapsulation comprising the solid encapsulation material, theencapsulation comprising a three-dimensional shape such that, along atleast one line in a direction perpendicular to and above the surface ofthe semiconductor device, starting from the surface, there is a gas orliquid or solid other than the solid encapsulation material, then thesolid encapsulation material.
 13. The method of claim 12, wherein theliquid encapsulation material is a liquid photopolymer resin and thesolid encapsulation material is a solid polymerized resin.
 14. Themethod of claim 12, wherein the three-dimensional shape is such that,along at least one line in a direction perpendicular to and above thesurface of the semiconductor device, starting from the surface, there isthe solid encapsulation material, then the gas or liquid or solid otherthan the solid encapsulation material, then the solid encapsulationmaterial.
 15. The method of claim 12, wherein the three-dimensionalshape comprises at least one specified cavity, channel or hole in theinterior of the three-dimensional shape.
 16. A method for encapsulatinga semiconductor device, the method comprising: a) imaging a surface ofthe semiconductor device, and comparing results of the imaging to adesign layout database of the semiconductor device to determineas-written locations of semiconductor device features; b) applying alayer of liquid encapsulation material to a surface of a semiconductordevice; c) modifying intensity of energy to be used, duration of energyapplication, and/or locations to be targeted in polymerizing the layer,in dependence on the imaging and the comparing; d) polymerizing targetedportions of the layer of liquid encapsulation material using targetedapplied energy, using the modified energy intensity, duration of energyapplication, and/or locations produced by the modifying, to form solidencapsulation material mechanically coupled to the semiconductor device;and e) repeating the steps a), b), and c) to form a specifiedthree-dimensional shape encapsulating the semiconductor device.
 17. Themethod of claim 16, wherein the liquid encapsulation material is aliquid photopolymer resin and the solid encapsulation material is asolid polymerized resin.
 18. The method of claim 16, wherein the imagingincludes imaging the solid encapsulation material, and wherein thecomparing includes comparing results of the imaging to a design layoutdatabase of the semiconductor device and of the three-dimensional shapeto locate placement errors of the solid encapsulation material.